Dupré, J. (1995) "The Solution to the Problem of the Freedom
of the Will" Philosophical Perspectives 10 385-402

The Solution to the Problem of the Freedom of the Will

John Dupré

Department of Philosophy

Birbeck College, University of London

Malet Street, London, WC1E 7HX

(0171) 631 6383/6549 Fax: 0171 631 6564

and

School of English and American Studies

University of Exeter, Exeter, EX4 4QH

(01392) 264267/264257 Fax: 01392 264361

It has notoriously been supposed that the doctrine of determinism conflicts
with the belief in human freedom. Yet it is not readily apparent how indeterminism,
the denial of determinism, makes human freedom any less problematic. It
has sometimes been suggested that the arrival of quantum mechanics should
immediately have solved the problem of free will and determinism. It was
proposed, perhaps more often by scientists than by philosophers, that the
brain would need only to be fitted with a device for amplifying indeterministic
quantum phenomena for the bogey of determinism to be defeated. Acts of
free will could then be those that were initiated by such indeterministic
nudges. Recently there has been some inclination to revive such a story
as part of the fallout from the trend for chaos theory. Chaotic systems
in the brain, being indefinitely sensitive to the precise details of initial
conditions, seem to provide fine candidates for the hypothetical amplifiers
of quantum events.

But this whole idea is hopeless. I need only recall that the interest
in establishing free will is not the conviction that humans are random
action generators, but a concern that human autonomy is inconsistent with
the possibility of fully explaining human actions in terms that have no
apparent connection with the wishes and beliefs of the human agent.1
Standard compatibilist claims that human autonomy and mechanistic causal
explanation are not mutually exclusive may or may not be defensible. But
the attempt to reconcile human autonomy with the complete randomness of
human actions is surely hopeless.2 At first sight it appears
that, despite the initial worries about determinism, indeterminism makes
the conception of freedom of the will even less tenable.3

Despite the untenability of the ideas just mentioned, my aim in this
paper will be to show that the solution to the problem of the freedom of
the will does lie, nevertheless, with the truth of indeterminism. To see
how this is so, it is necessary first to distinguish two very different
grades of indeterminism. The indeterminism entailed by the common understanding
of quantum mechanics, while it denies that the causal upshot of a situation
is a determinate function of any fact about that situation, still insists
that there is a complete causal truth about every situation. It is just
that this truth is in the form, not of a unique outcome, but of a range
of outcomes with specific probabilities attached to their occurrence. Thus
situations are still conceived as evolving according to laws, just laws
of a somewhat different kind. I shall refer to both determinism, and this
brand of moderate indeterminism, as versions of the thesis of causal completeness.
Even if determinism is false, causal completeness requires that there be
some quantitatively precise law governing the development of every situation.
If we maintain the doctrine of causal completeness, then the only retreat
from physical determination of our actions is in the direction of more
or less unreliability, hardly a desirable philosophical goal. However,
the indeterminism that I wish to advocate is something quite different,
the denial of causal completeness. I shall maintain that few, if any, situations
have a complete causal truth to be told about them. Causal regularity is
a much rarer feature of the world than is generally supposed. And the real
solution to the problem of freedom of the will, I shall argue, is to recognize
that humans, far from being putative exceptions to an otherwise seamless
web of causal connection, are in fact dense concentrations of causal power
in a world where this is in short supply.

The solution to the problem of human autonomy that I propose, then,
is a complete reversal of traditional non-compatibilist approaches. Such
solutions have assumed that the non-human world consists of a network of
causal connections, the links in which instantiate lawlike, exceptionless
generalizations, but tries to show that humans, somehow, lie outside, or
partially outside this web4. By contrast, I am suggesting that
causal order is everywhere partial and incomplete. But humans, by virtue
of their enormously complex but highly ordered internal structure, provide
oases of order and predictability. Thus the significance of recognizing
indeterminism is not at all to show that human actions are unreliable or
random. It is rather to show that the causal structure that impinges on
a human being, whether externally from macroscopic causal interaction,
or internally, from constitutive microstructural processes, is not such
as to threaten the natural intuition that humans are, sometimes, causally
efficacious in the world around them.

This picture immediately accords with some obvious empirical facts:
among the most apparently orderly features of the external world, such
as straight roads and vertically stable edifices, not to mention complex
machines, are products of human action; and among the most predictable
entities in the world, as Hume, to a rather different purpose, argued,
are people. Plans can be coordinated among many people, and complex human
institutions can function, because human behavior is to a substantial degree
reliable. All of this is quite unproblematic if we see humans as sources
of causal order rather than either as exceptions to a universal external
order or as insignificant components of some all-encompassing cosmic order.
Thus a radical rejection of the traditional mechanistic assumption of causal
completeness does indeed defuse the traditional problem of free will.

I shall expand on these claims at various points in this paper. Prior
to that, however, the main task of the paper will be to render its presuppositions
plausible. In the next part of the paper I want to argue that determinism,
specifically microphysical determinism, really is a problem for an adequate
account of human autonomy. Thus I reject the post-Humean compatibilism
that holds no amount of determinism to provide any difficulty for freedom
of the will. In the third section, I shall argue that we have, fortunately,
no reason to believe in determinism--or even causal completeness, whether
microphysical or any other kind. The paper will conclude with some further
discussion of how I conceive the rejection of causal completeness to provide
a way out of the traditional problem of free will.

Microphysical Determinism and the Causal Inefficacy of Everything Else

Suppose that there is some set of microscopic entities undecomposable into
any smaller constituents, and of which all larger entities are composed.
Assume that all putative entities that might appear not to be composed
of anything (numbers, abstract objects, universals, etc.) are either wholly
dependent for their existence and behavior on objects made of these microscopic
entities, or non-existent. Though these suppositions could certainly be
questioned, I believe that they would be widely accepted among the many
philosophers who think of themselves as physicalists. Now suppose that
we also have a fully deterministic account of the behavior of these microscopic
entities. Although heroic attempts have sometimes been made to deny it,
it seems to follow inevitably from this set of assumptions that the behavior
of everything is fully determined by the laws at the microlevel. This seems
to follow immediately from the assumption that objects at higher levels
are composed entirely and exhaustively of the microscopic objects. For,
given the assumption of determinism, it is true of every individual microscopic
object that its behavior is fully determined by the laws governing microscopic
objects. And surely if the behavior of every constituent of a thing is
determined, so is the behavior of that thing.

This point can be made more graphic by thinking of a constituent of
a human being, say an electron in my finger. I might be inclined to explain
the movement of that electron by saying, for example, that I was reaching
for a glass of water, and my hand brought the electron along with it. But
clearly this explanation is going to have to be consistent, at the very
least, with the explanation in terms of the microphysical laws acting on
the electron. If we now consider the same condition applying to all the
various electrons and suchlike in my arm, it would appear that only cosmic
coincidence or some kind of dependence of the higher level on the processes
at the lower level could insure this overall compatibility. The bold conclude
at this point that either the higher level phenomena are reducible, in
the sense of derivable, from the lower level phenomena, or they cannot
really exist at all (elminativists). The more cautious fall back on claims
of supervenience, though as far as I can tell this is merely reductionism
with a modest reticence about the capacity of humans to carry it out. At
any rate, none of these positions allows any genuine autonomy to the higher
structural level5.

The importance of emphasizing the concept of causal completeness rather
than merely determinism is that nothing is significantly altered in the
preceding argument by moving from a deterministic to an indeterministic
but complete system of laws at the microlevel. Given my intention to drink
from the glass of water in front of me, the probability that the electron
referred to in the preceding paragraph will move in a certain direction
is very high. Again there must be some parallel explanation at the microlevel
that also attributes a similar high probability to such a move. And again,
when we aggregate all the particles that compose my arm, some explanation
is required of the apparently extraordinary coincidence between the phenomena
at the two levels.

My general point is just that causal completeness at the microlevel
appears to entail reductionism, at the very least in the sense of the supervenience
of everything else on the microphysical. And even supervenience, I claim,
is sufficient to deny any real causal autonomy to higher structural levels.
The alternative picture I would like to advocate denies causal completeness
at any level. Objects at many, probably all, levels of the structural hierarchy
have causal powers. One of the reasons why these causal powers are never
displayed in universal laws (deterministic or probabilistic) is that objects
at other levels often interfere with the characteristic exercise of these
powers6. I take it that the example of the electron in my hand
is best seen as such a case.7 If that is right, then the behavior
of microlevel objects is very frequently consequential on processes at
higher structural levels. As a simple example in the opposite direction,
a person's plans can be seriously impeded by a dose of radiation. Elsewhere
I have also advocated ontological pluralism at particular structural levels
against the essentialism that tries to insist on a uniquely privileged
position for one set of kinds. My present claim is that the same ontological
tolerance should be accorded between structural levels. As objects are
united into integrated wholes they acquire new causal properties (perhaps
that is exactly what it is for a whole to be--more or less--integrated).
I see no reason why these higher level wholes should not have causal properties
just as real as those of the lower level wholes out of which they are constructed.
But of course many philosophers have seen many such reasons, all grounded,
I suggest, in the conceptual nexus that links determinism (or at least
causal completeness) and reductionism. I believe that both of these doctrines
are inherently implausible, but because the former is more widely, or at
least explicitly, believed, and because it is more closely and traditionally
associated with the question of human freedom, in this paper I shall focus
exclusively on causal completeness. To this, the central task of this paper,
I shall now turn.8

Causal Incompleteness

The thesis of this section of the paper is that there is no plausible ground
for the belief in determinism. I shall address most of the argument to
the doctrine of determinism, but I intend that everything I say will apply
equally to indeterministic versions of causal completeness unless I explicitly
differentiate the two cases. Later in the paper I shall say something about
how I conceive of causal reality in the absence of the assumption of causal
completeness. The basic strategy of my argument will be as follows. Presumably
determinism is a very strong metaphysical assumption. To claim that everything
that happened had to happen, given the totality of prior conditions, is
to impose an enormously strong--indeed the strongest possible--restriction
on the possible evolution of the universe. And even the claim that the
state of the universe at any time fully determines a set of objective probabilities
for its subsequent state is a strong assumption. My point is then that
such strong assumptions require persuasive reasons if they are to have
any plausibility. I do not take seriously the idea that determinism might
be established by means of a transcendental argument of some kind, simply
because, as I shall explain below, an indeterministic, causally incomplete,
world seems to me entirely possible. Thus my question will be whether there
is any basis in our empirical interaction with the world for supposing
that it is causally complete. My answer will be in the negative.

There are two main kinds of experience that might be held to legitimate
a belief in determinism. These are our familiarity with scientific laws
and our everyday causal experience. An important special case of the latter
is our experience of highly organized systems, especially machines and
organisms. I shall deal with these topics in turn, but reserving the special
cases of machines and organisms to a separate section. First, then, do
the results of scientific investigation lend support to the idea that the
world is deterministic, or at any rate causally complete? Here I must first
dispose of an important red herring. It is often claimed that science must
assume determinism as a methodological imperative. The idea is that it
would be sheer defeatism, when confronted with a phenomenon anomalous in
the light of current belief, to assume that this was simply a phenomenon
outside the causal nexus. We naturally and correctly attempt to broaden
our understanding of the range of phenomena in question so as to remove
the appearance of anomaly. But that, it is claimed, is to assume that the
anomalous phenomenon is in fact part of a uniform and complete causal nexus.
Thus it might be suggested (and this is the non sequitur) that science
must assume determinism; and then perhaps, that the successes of science
provide evidence that the presuppositions of science, in particular determinism,
must be true. But of course to say that science aims to explain phenomena
does not entail that all phenomena can be fully explained. And to say that
science has had some explanatory successes hardly implies that everything
that happens can be fully explained as part of an underlying universal
regularity.

So do the actual results of scientific research provide more direct
evidence for determinism? The most compelling such results, for the reasons
spelled out in the preceding section, would be those that provided evidence
for casual completeness at the microlevel. But clearly there is no such
evidence. Although certain very specialized phenomena in extremely carefully
controlled conditions do exhibit some impressive regularities, this is
the entire extent of such evidence. (As should become apparent later on,
the fact that these regularities are produced in extremely elaborate machines--machines
painstakingly designed for the very purpose of producing these regularities--is
of great significance.) Evidence for causal completeness would require
that increasingly complex systems of physical particles could be shown
to be amenable to causal explanation in terms of the laws said to govern
individual particles, evidence, that is to say, for general reductionism.
I cannot here go into the general difficulties that confront the project
of reductionism. But I do not need to do so. No one has claimed to be able
to explain the behavior even of very small collections of particles in
terms of the behavior of individual particles; the reduction even of relatively
simple parts of chemistry to physics is now looked on with considerable
skepticism; and even physics itself is acknowledged to consist of laws
the relations between which are obscure, though at least the unification
of physics is still looked upon by some physicists as an attainable goal.
At any rate, the view that every physical particle has its behavior fully
determined by microphysical laws must derive any plausibility it has from
some source other than the development of microphysics.9

It appears then that microphysical determinism must be motivated, somewhat
paradoxically in view of the connections between determinism and reductionism,
by experience at the macroscopic level. But before turning to our everyday
experience of causal regularities we might consider the possibility that
microphysical determinism could be motivated by our knowledge of macrophysical
laws. The obvious candidates, since they remain the most widely admired
paradigm of scientific knowledge, would be the laws of Newtonian mechanics.
But here we encounter exactly the same difficulty that we saw at the microlevel.
Whereas scientists have been able to subsume very simple systems such as
the solar system under impressively reliable regularities, the ability
to apply Newtonian laws to more complex systems has proved severely limited.
The notorious failure to solve the three-, let alone N-, body problem marks
this failure. Thus we have no empirical evidence for the general truth
of Newtonian mechanics as applied to complex systems of bodies unless we
are prepared to countenance inductions grounded on one kind of case (very
simple systems) to all cases, most of which are very different from those
empirically studied. Moreover, to reiterate a point emphasized by Nancy
Cartwright(1983), we know that laws such as those
of Newtonian mechanics are true only under a very stringent ceteris
paribus condition, a condition we know to be generally false. Thus,
far from knowing that these laws are universally true, we know that they
are generally false. The assumption that the laws of Newtonian mechanics
are, in some sense, carrying on regardless under the overlay of increasingly
many interfering and counteracting forces is sheer speculation. Thus this
can hardly be a good empirical ground for the alleged universality of microphysical
laws.10

The other common idea, mentioned above, is that determinism is evident
from our everyday experience of causality. This assumption can be seen
in classical regularity theories of causality from David Hume to J.S.Mill
and J.L.Mackie11. Hume appeared to take determinism outside
the human sphere to be so obvious as not to need much discussion. He was
more concerned to show, with well-known examples such as the sure and swift
appropriation of a purse of gold abandoned at Charing Cross, that humans
were subject to regularities just as immutable as those governing the natural
world. Mill was a good deal more sensitive to the complexities of regularities
of the latter kind, realizing that the regularities of common experience
could easily enough be defeated by either the absence of necessary background
or auxiliary conditions, or by the presence of interfering conditions.
Thus a lighted match thrown onto a pile of dry straw will always start
a fire--unless, that is, there is no oxygen, or a fire extinguisher is
simultaneously directed at the straw, etc. While thus acknowledging the
complexity of everyday causal regularities, Mill appears to have thought
that with sufficient care to include all the relevant auxiliary conditions
and exclude all possible blocking conditions, a truly universal regularity
could be discovered. This idea reached its most sophisticated expression
with Mackie's analysis of an everyday cause as an insufficient but non-redundant
part of an unnecessary but sufficient condition, or an "inus" condition.
The sufficient condition in this analysis is the cause with all the auxiliary
conditions and the negation of possible interfering conditions. The non-necessity
of such conditions points to Mackie's additional recognition that there
might be many such complex sufficient conditions of which none, therefore,
would be necessary (a bolt of lightning might equally well have ignited
the pile of straw).

Many objections can be raised against this picture, at least if it is
assumed that it intends one to take seriously the universality of the implied
laws rather than merely to illuminate the relations between miscellaneous
items of causal lore. One may well doubt, to begin with, whether there
is any definite limit beyond human imagination to the number of conditions
that we might need to add to produce a fully universal generalization.
More seriously, the more conditions are added, the further these putative
regularities recede from any possibility of empirical support or refutation.
Indeed the reason we are forced to move from simple regularities (e.g.
lighted matches cause fires in flammable materials) to increasingly complex
and qualified regularities is simply because we recognize the general falsity
of the simpler ones. But as we move to such ever more complex regularities,
first, the amount of evidence even bearing on the truth of the regularity
will rapidly decline; and second, in keeping with the process that brought
us the complex regularity in the first place, were we to find an exception
to the complex regularity we would presumably respond by looking for a
further interfering condition rather than by rejection of the entire regularity.
This suggests that the Mill/Mackie program might better be seen as embodying
a methodological rather than a metaphysical conception of determinism.

A second kind of objection casts doubt on the empirical basis of everyday
causal determinism from a rather different perspective. Many everyday phenomena
give no superficial appearance of being deterministic or even nearly deterministic.
Consider, for example, a tossed coin. Now it is often asserted that this
is a fundamentally deterministic phenomenon, and the only reason we are
unable to predict the outcome is that we have an insufficiently precise
knowledge of the initial conditions. It is much less clear why this is
asserted. Presumably it must be because the kinds of laws involved in such
a process (mainly Newtonian) are assumed to be deterministic. But I have
already considered the weakness of that line of thought. The present case,
since it is one in which we cannot in fact make any such predictions, provides
further support for the argument against basing determinism on macroscopic
scientific laws. At any rate, the thesis that everyday causal experience,
suitably refined in the style of Mill and Mackie, provides grounds for
the belief in determinism, simply ignores the fact that a great deal of
our experience, whether of gambling devices such as tossed coins and roulette
wheels, or just of seemingly quite erratic natural phenomena such as falling
leaves or swirling smoke, provides no such grounds.

The final argument I shall mention is perhaps the most telling. It is
that if there is causal indeterminism anywhere, it will surely be (almost)
everywhere. Suppose, as is sometimes rather bizarrely suggested, that the
only locus of indeterminism is in quantum mechanics. But surely--and here
phenomena such as hypothetical quantum amplifiers in the brain have genuine
significance--it must be impossible to insulate the indeterminacy of quantum
events so fully from consequences at the macroscopic level. Consider again,
for instance, the tossed coin, and suppose that its trajectory deterministically
produces--ceteris paribus--its final outcome. Suppose the coin is
at a point at which it is about to land heads. And suppose finally that
a collision with a fast-moving air molecule is sufficient to reverse this
outcome and produce a toss of tails. If the situation is sufficiently delicately
balanced this must surely be possible. Assuming that the molecular trajectory
is a sufficiently microscopic event to be subject to some degree of quantum
indeterminacy, then we can easily see that the claim to determinacy of
the coin-tossing event cannot be sustained. We cannot treat this as merely
another interfering factor, because whether or not it has any effect on
the final outcome cannot be determined by any amount of knowledge of the
initial conditions.

It is a further advantage of this example that a coin toss is the kind
of event that might imaginably have massively ramifying consequences. Perhaps
the last degenerate scion of some aristocratic line is wagering his fortune
on this coin toss. The outcome will dramatically affect the lives of his
dependents, servants, creditors, etc. and their fortunes will have an increasing
cascade of consequences. (This sort of thing will be familiar to readers
of Victorian novels.) The general point that this argument is intended
to illustrate is that indeterminism anywhere, by virtue of the variety
of causal chains that might be initiated by an indeterministic event, is
liable to infect putatively deterministic phenomena anywhere. It is significant
that this applies equally within and across levels of structural complexity.

One final point will conclude this section. The last argument discussed
is an argument against determinism, but not necessarily against causal
completeness. In the case of the coin toss, provided only there is no correlation
between interfering molecular events and outcomes, we should expect that
these would be equally likely to change heads to tails and vice versa.
So even if these interfering events occurred in accordance with no law
even of a statistical nature, they might not render incomplete the supposed
law that coins of a certain kind come up heads 50% of the time. On the
other hand the preceding arguments, based ultimately on the lack of empirical
support for determinism, seem if anything even more pressing against an
indeterministic version of causal completeness. For any investigation of
a range of phenomena will provide statistical facts. That, for some x,
x% of events of type A are followed by an event of type B, is a matter
of logic. But for this very reason, even if we have excellent grounds for
believing that As really do have a tendency to produce Bs, it is difficult
to see why we should be led to believe that there is any x such that it
is a law that x% of As produce (or are followed by) Bs. The most
plausible basis for such a belief, I suppose, would be microphysical reductionism,
a topic about which I have said as much as I have space for here. We might
better ask, What would it mean for there to be a law of this kind,
as opposed to there merely being a tendency of As to produce Bs, and a
statistical correlation of a certain strength between As and subsequent
Bs? Ignoring for the present purposes a range of widely explored subtleties
concerning spurious and genuine correlations, joint effects of a common
cause, and so on, which would be required for a detailed answer to this
question, the simple answer which is sufficient for my present purposes
is just that a precise causal law should license us to expect that the
proportions measured in a suitably large numbers of trials should be (approximately)
repeated in the future. It seems to me, on the contrary that in practice
such an expectation would often be foolhardy.

In real life, the degree to which we treat statistical experience as
a guide to future expectations will vary from almost zero to almost unity.
No doubt many explanations could be given of the reasonableness of such
a perspective, some consistent with causal completeness. The explanation
which seems to me most consistent with both investigative practice and
the experience of causal regularity, however, has nothing to do with laws
or statistical uniformities at all. Correlations reveal, I believe, (subject
to well-known qualifications) the causal powers of certain objects or events
to produce particualr effects. Whether we expect the production of such
effects to occur with a fairly constant frequency depends whether we think
that the frequency of other relevant causal factors is likely to remain
reasonably stable. But without some apparently quite arbitrary way of privileging
a particular constellation of background conditions, there is no such thing
as the quantitatively precise, constant and timeless tendency of As to
produce Bs ceteris paribus. Other things can be a particular way,
and they can be more or less reliably that way. But except in the very
simplest cases, as in Newtonian mechanics where we imagine there being
only two bodies in the universe, and everything else is supposed not equal
but absent, I do not know what everything else being equal even means.
Thus once we have fully appreciated the complexity of the causal nexus,
the thesis of indeterministic causal completeness is seen to be not only
devoid of empirical support, but even to be of dubious intelligibility.

Machines and Organisms

As I have tried to show in the preceding section, I do not think that direct
reflection on our (extremely limited) knowledge of universal regularities
lends much support to the idea of a universe with a complete causal structure.
However it may well be that deterministic intuitions derive more from reflection
on complex and highly organized structures, especially machines and biological
organisms. Since the overall metaphysical vision out of which the whole
problem of free will arose is aptly referred to as mechanism, it is certainly
appropriate to consider the artefacts that have somehow come to provide
a model for the universe; the consideration of organisms, notoriously liable
to be treated as a kind of naturally occurring machine, will bring us back
to the topic with which this paper began, the causal status of humans.

It is easy enough to see why machines should have some tendency to inspire
deterministic intuitions. Machines, good ones anyhow, are extremely predictable.
I am confident that the text I type into my computer is exactly what will
eventually come out of my printer when I connect them up in the right way.
(Though not so confident that I do not occasionally make a hard copy; and
some people, I am told, even make back-ups of their computer files on disks.)
But a little further reflection makes it very puzzling that something like
this, rightly admired as one of the great triumphs of modern technology,
should be taken as a model for the universe in general. If the sort of
regularity that is characteristic of a good computer or car were typical
of the universe it would, one might imagine, be fairly easy to make, or
perhaps even just find, such things. But it is not at all easy, which is
why such technological achievements are admired. If the universe is a machine,
it is far from obviously so.

Perhaps a more sympathetic interpretation of the tendency for machines
to inspire determinism is the idea that only if determinism were true would
it be possible to make reliable machines. And since we can make reliable
machines, determinism is proven to be true. Underlying what seems to me
a great exaggeration in the first premise there is, nevertheless, a very
interesting question: what degree of order must exist in the world for
the kinds of reliable machines we possess to be possible? The beginning
of a more temperate answer to this question than the immediate appeal to
determinism is the observation that no machines are completely reliable,
and some are very unreliable. The point of this observation is not to insist--though
strictly speaking it is no doubt true--that there is some possibility,
however remote, that when I type the word "type" on my computer a four-letter
obscenity will instead appear on the screen; or that when the spark ignites
in the combustion chamber of my car the gasoline inside it will spontaneously
liquefy. Rather I want to focus on the question, what is it that makes
machines more or less reliable. And of course the answer is not, at any
rate, that reliable machines have access to more universal laws.

Consider, then, what is by modern standards a fairly simple machine,
an internal combustion engine. If we ask how such a machine operates we
may be content with a very simple story: a mixture of air and gasoline
is exploded in a cylinder, pushing a piston down the cylinder; the cylinder
is connected to a shaft which is rotated by the moving piston. A number
of similar cylinders are connected to this shaft, and a sequence of explosions
keeps the shaft rotating continuously. It seems to me that this is, roughly
speaking, a correct answer to the question how an internal combustion engine
works. But if, on the basis of this explanation, someone lined up some
coffee cans partially filled with gasoline on the kitchen floor, stuck
toilet plungers in the cans and tied the ends of the plungers to a broomstick,
and then posted lighted matches through little holes in the side of the
coffee cans, they would certainly not have built an internal combustion
engine (though I suppose the broomstick might jump about a bit).

I suggest that it is useful to think of how a machine works in two stages.
First there is the question what makes it even possible for the machine
to do what it is supposed to do. A slightly more elaborate version of the
answer sketched in the previous paragraph might be an answer to this question
for an internal combustion engine. Having got that far, however, most of
the details of the internal combustion engine concern the more or less
ingenious auxiliary devices that make sure it really does do what it is
intended to do rather than one of the may other things it has an initial
capacity to do. So, for instance, the cylinder must be strong enough to
avoid simply disintegrating when the gasoline explodes; the crankshaft
must be extremely strong and rigid if it is to reliably convert the linear
momentum of the cylinders to rotational motion; piston-rings prevent the
energy of the explosion from being dissipated between the piston and the
cylinder; oil must be provided to prevent the cylinders getting so hot
as to seize in the cylinder, or for that matter melt; some way must be
found to dissipate excess heat from the running engine; and so on. Even
a Trabant has the capacity to run, and sometimes does so. The difference
between this and a well designed car is that the behavior of the parts
of the latter is so tightly constrained that it can do nothing but what
it is designed to do--though eventually, of course, even the best designed
machine will break free of its constraints. My point so far is just that
this kind of constraint is not something characteristic of nature generally,
but something that engineers devote enormous efforts to attempting, never
with total success, to achieve.

Of course, this account of the reliability of machines does assume the
reliability of various causal relations. Gasoline and air mixtures invariably
explode when sparked; heat will flow from a hot engine to cooling water
circulating over it; and many others. It is interesting that many such
regularities can be seen as reflecting the overall upshot of very large
numbers of similar though indeterministic processes at the microlevel,
which suggests the hypothesis that it is just those macrolevel processes
that can be roughly reduced in this way that reveal this near determinism.
But I do not want to insist on this here. While machines could presumably
not work without exploiting extremely reliable regularities such as those
just mentioned, the regularities that characterize the machines themselves,
as with many other macroscopic causal regularities are only more or less
reliable. Reflection on how good machines are engineered, far from making
us think of mechanism as generally characteristic of the world, should
make us realize how difficult it is to turn even little bits of the world
into bits of mechanism.

Turning now to organisms, it is a familiar idea, especially following
Descartes, that organisms just are machines. Natural theology until the
late nineteenth century considered organisms quite explicitly as the products
of a divine mechanic. No doubt there are aspects of organisms for which
this analogy is illuminating. Indeed the complex but highly stereotyped
performances of many insects in, for example, constructing and provisioning
burrows for egg-laying have many of the characteristics of a well-designed
machine. To the extent that the analogy is appropriate the same remarks
that I made about machines will apply to the relevance of organisms to
the prevalence of causal regularity. Looking, however, at the other end
of the organic scale, and most especially at humans, the parallel with
machines has serious limitations.12

The fact that when, for example, I intend to walk down the garden path,
my legs move in just the right way to maintain my balance and propel me
forward is, I suppose, something that could be explained in a manner strongly
analogous to the performance of a machine, though perhaps more complex
than any machine we have yet managed to construct. I suppose that the physiology
and cell-chemistry of muscle tissue explains how the physical movements
are obtained, and a variety of sensory and neural mechanisms bring it about
that the motion is steady and in the right direction, and that a vertical
posture is maintained. Although this seems significantly analogous to the
account I offered of the working of the internal combustion engine, we
should now note that an internal combustion engine is in reality not a
machine but a part of a machine. If we think now not just of an engine
but of an entire car, an important class of features has yet to be mentioned.
I am thinking of such things as the ignition key, the steering wheel, and
the brake pedal, those devices by which the machine is made to act in a
way conducive to the ends of its human operator. A reliable car, as opposed
to a reliable engine, the latter of course being a necessary but insufficient
component of the former, is one in which there is a reliable correlation
between inputs to these controls and the behavior of the whole machine.
Thus machines are not sources of causal autonomy; they are, at most, instruments
for furthering the causal autonomy of their users. The superficial, and
I think also deep, disanalogy between humans and machines is that humans
have no controls.

It may rightly be objected at this point that insects with simple stereotyped
behaviors have no controls either, yet I have claimed that they are closely
analogous to machines. There are two possible responses. First, a stereotypical
performance might simply be produced in response to nothing at all. More
typically and interestingly, a kind of behavior might be triggered by some
sensory input, the sense organs thus serving as devices for producing behavior
appropriate to the external circumstances. This is primarily what I have
in mind in talking of the stereotypic and machine-like behavior of certain
insects: a certain stimulus triggers a sequence of behavior. There is,
of course, a tradition of psychological investigation of humans that applies
just this model to humans. Though in it crudest behaviorist versions it
has been almost wholly rejected, the idea that sensory inputs, mediated
by "information-processing mechanisms," somehow elicit the appropriate
"emission" of behavior is still widely, perhaps generally, pursued. This
is a mechanistic model, though one in which the complexity of the machine
is such that we as yet have no idea what it is designed to do in the innumerable
situations it encounters.13 Against this model, I propose that
we should recognize that we were not designed at all, and consequently
there is nothing we were designed to do in any situation.

Between two views that I have rejected, that we are random action generators
and that we are machines, can be found the view that makes sense of human
autonomy. Many parts of humans have just the characteristics of machines
that I have emphasized in the preceding discussion, namely complex constraints
that insure the predictable exercise of somecapacity of an organ or physiological
system. But humans are fundamentally different from machines in that they
have no controls. Self-control, in the sense of the absence of external
controls, is of course nothing but the autonomy, or free will, that was
the original topic of this paper. I have not attempted to refute the idea
that sense organs might sometimes function as controls, in the sense that
the input to sense organs might determine, via a complex intermediate causal
chain, the behavior of the whole organism. This is presumably roughly true
of simple organisms. But it does not appear to be true of ourselves, except
perhaps in purely reflexive actions, such as ducking to avoid a flying
object. The reason we are so liable to think of ourselves in this machine-like
way is because we are tempted by determinism. If the world is deterministic
then my behavior is causally necessary given the stimuli that impinge on
me; and presumably the most important stimuli are sensory ones. The point
of all the complex machine-like parts of me would then have to be just
to make sure that the causally elicited behavior was appropriate to the
circumstances disclosed by my sense organs. But the rejection of causal
completeness allows a more natural view of things. My complexity of structure
gives me a vast array of causal powers, a range of powers that would be
inconceivable without that intricate machine-like internal structure. But
the exercise of those powers, though obviously influenced by the circumstances
I perceive myself to be in, ultimately depends on an autonomous decision-making
process. Once we see causal order as something special rather than something
universal, there is no obstacle to seeing the human will as an autonomous
source of such order.

Some Concluding Remarks

My reference at the end of the last section to the human will leaves, needless
to say, some questions unresolved. However, it is not my goal here to offer
a detailed account of the will. Rather, my more modest aim is to show that,
contrary to a notorious tradition of philosophical controversy, a reasonable
metaphysics of causality presents no special difficulties for the idea
of human autonomy, and requires neither ghostly nor random nudges of the
physical causal order. In order to give a little more positive philosophical
substance to the view I shall, in this final section, very briefly relate
what I have said to some very famous views on the subject, those of Hume
and of Kant.

Although it may well remain the dominant view of the subject, Hume's
attempt to reconcile human autonomy with a classically deterministic structure
of causal relations seems to me unconvincing14. On the other
hand Hume was surely right that exercises of human freedom were much better
understood as instances of causality than of its complete absence. His
problem, in my view, was his commitment to a universalistic regularity
theory of causality. Given such an account of causality, any departure
from determinism is a failure of causality itself.15 The solution
I have advocated requires espousing an ontology of causal powers of the
kind that Hume so famously attacked.16

Kant also appears to have thought that a deterministic causal structure
was compatible with human autonomy, though the metaphysical excesses to
which he was led in effecting this reconciliation have convinced almost
no one. However his conception of human autonomy might provide--though
here I end on a more speculative note--a vital and final piece in the picture
that I wish to present. My point at the end of the last section was that
human decision could be a real source of causal order in the world. However,
this claim may seem shallow without some further account of the origins
of this order. In particular if one traces human decisions ultimately to
contingent human desires, desires which presumably can themselves be traced
either to our biological heritage or our upbringing, human autonomy seems
at best a focus rather than a source of order. And just such a conception
of human decision-making has been cultivated for a century by economists
and more recently by exponents of so-called rational choice theories in
a variety of disciplines. Some more interesting account of the ultimate
springs of human behavior than the economist's standard refrain, "tastes
are exogenous," is needed if we are to provide a deeper and more interesting
conception of human autonomy.

Without going into what I take to be the deficiencies of the economistic
vision of human behavior, it is clear that something more than an unexplained
appeal to particular tastes or preferences is required to give interest
to the account of human autonomy suggested in this paper. It seems to me
that Kant's account of human action suggests a promising direction in which
to go. Kant, notoriously, distinguished sharply between action motivated
by desire and action motivated by principle. Having dispensed with the
deterministic framework, it is possible to emphasize this distinction without
either the extreme moralistic distinction in favor of action motivated
by duty, or the metaphysically murky appeals to the noumenal world, which
have combined to cast deep suspicion on Kant's conception.

In a world where order is a local and incomplete phenomenon, the importance
of principle as a source of human action is easily stated: it explains
how ideas, the creative acts of the human mind, can change the world. Unlike
Kant, I do not make a fundamental distinction here between moral and more
mundane principles. I conceive of the principle, "Follow the architect's
blueprints in determining where to build the wall," as as genuine a source
of autonomous action as "Do whatever is necessary to end hunger." But despite
this moderation of the Kantian position, the enormous importance of moral
principles in this context should not be downplayed. The most fundamental
reason why we should care about human autonomy is that it holds out the
hope that human action might produce a better world. And what that requires
is action grounded in moral principles. This is something I believe we
are free to choose; and making this choice, I claim, can make a difference.

I conclude with one further speculative and perhaps paradoxical suggestion.
Principles, I take it, are essentially linguistic phenomena. And language
is essentially social. Thus the condition for genuinely free individual
action is the embedding of the individual in society. This will not seem
surprising to those who take seriously the fundamental biological fact
that Homo sapiens is a social animal. It may, however, be an unwelcome
suggestion for the tradition that connects human freedom with the profoundly
individualistic social philosophy and metaphysics dominant in contemporary
English-speaking culture. That, however, is not my concern.17

Notes.

1. No doubt the belief in such indeterministic events was often also connected
with the inchoate hope that these might be sufficiently loose and microscopic
that even an immaterial soul might have a chance of subtly influencing
them. Though this make the idea less absurd from the point of view of understanding
human autonomy, it intorduces new absurdities that I cannot attempt to
address here.

2. This point was clearly stated by C. D. Broad (1952).

3. And presumably for this reason the possibility of indeterminism does
not figure largely in recent discussions of the problem of free will. In
a recent anthology on the topic (Fischer 1986), I could find only one extended
discussion of the topic, in the paper "Asymmetrical Freedom" by Susan Wolf.
However even this discussion concerns only the failure of determinism at
the psychological level, and remains agnostic about the relation of this
to underlying physical determinism. Because of this difference in focus,
I shall not try to relate the present discussion in any detail to recent
philosophical work on the topic.

4. A classic statement of such position is that of William James (1884/1956).

5. This is at the basis of Kim's well-known arguments against non-reductive
physicalism (Kim1993, especially essays 14 and 17) . Kim shows that such
a position requires "downward causation" the causal influence of macroscopic
on microscopic entities. I accept the argument but, as will be clear below
and as I have explained elsewhere (1993), I see no problem with downward
causation.

6. As of course may objects at the same level. This kind of objection
to universal regularities has been emphasized by Cartwright (1983).

7. It will be objected--and may already have been objected--that the
electron will be pushed by the microscopic object or objects immediately
behind it and will push those in front of it, and thus all the particles
are moving in response to microlevel forces. I do not mean to deny this:
certainly it would be absurd to suppose that my intention independently
acted on each particle in my arm. The real issue is whether all these arm-particles
are moving as part of a much wider set of microphysical events (photons
bouncing of the glass, hitting my retina, stimulating my brain, etc.) on
which my intention to drink the water is ultimately a mere epiphenomenon,
or whether, rather, the fundamental explanation for all those particles
pushing one another in a certain direction is that I am thirsty and see
a glass of water I plan to drink. Evidently I prefer the latter view.

8. The various theses referred to briefly in this paragraph are defended
in detail in my book, The Disorder of Things: Metaphysical
Foundations of the Disunity of Science(1993). Part 1 of that
work addresses essentialism, part 2 provides a detailed critique of physicalist
reductionism, and part 3 provides a more extended version of the arguments
against causal completeness developed in the following section of the present
paper.

9. It is of course true that microphysical laws purport
to apply to indefinitely complex systems, in the sense that they determine
how the formalism should, in principle, be applied to such systems. But
in practice they certainly cannot be so applied. And one need hardly be
a radical skeptic about induction to resist extrapolation from a very narrow
and limited set of data to every phenomenon whatever that could in principle
be subsumed under the purported regularity.

10. See Suppes (1994) for a more detailed argument complementary to
the present one.

11. See principally Hume (1748), Mill (1875), and Mackie (1974).

12. I focus here only on what I take to be the extremes of the animal
scale. I assume that higher mammals, birds, and perhaps higher molluscs,
are more like humans than they are like the most machine-like of insects.
But I shall make no attempt to here to draw any more specific lines between
different kinds of organisms.

13. Sociobiologists, evolutionary psychologists, and other extreme enthusiasts
for explanations in terms of natural selection believe that we have been
designed to survive and reproduce. The crudity of attempts to explain human
behavior in any detail on the basis of this thesis has been well documented--if
inadequately appreciated--and will not detain us here.

14. I cannot begin to discuss the enormous literature on this question.
Strawson's (1974) classic paper perhaps brings out as clearly as possible
the consequences of taking physical determinism fully seriously.

15. Recently there has been a prominent movement to provide regularity
theories of indeterministic causality (e.g. Eells 1991). I think there
are deep internal problems with such a position (see Dupré and Cartwright
1988; Dupré 1993, ch.9); and in defence of my commitment in the
present paper to address causal completeness more generally than in its
deterministic version, I think that such a position is fatally lacking
in empirical backing.

16. A detailed response to the Humean view of causality would be beyond
the scope of this paper. Some recent advocates of causal powers include
Harré and Madden (1975), Cartwright (1991), and Dupré (1993,
ch.9).

17. I am indebted to Regenia Gagnier, John Perry, and Debra Satz for
comments on an ealrier version of this paper.

Bibliography

Cartwright, Nancy. 1983. How the Laws of Physics Lie. Oxford:
Oxford University Press.